1. Field of the Invention
The present invention relates to a noise attenuator for attenuating noises generated from a compressor of a refrigerator, an air conditioner or the like, and more particularly to a noise attenuator of a compressor for attenuating noises generated from valves disposed within the compressor.
2. Description of the Prior Art
Generally, a compressor is constructed to comprise a driving unit and a compressing unit sealed in an airtight case 1, as illustrated in FIG. 1.
The driving unit comprises a motor, which in turn, is composed of a rotor 2 and a stator 3.
The rotor 2 is equipped with a rotary shaft 6.
The compressing unit comprises: a crank shaft 5 eccentrically jointed to a lower end of the rotary shaft 6 of the driving unit; a connecting rod 9 for transforming a rotary movement of the crank shaft to a reciprocating motion by being rotatively jointed to the crank shaft 5; a piston 7 for performing a reciprocating motion by being rotatively jointed to the connecting rod 9; a cylinder 8 for receiving the piston 7; and a head cover 4 jointed to one side of the cylinder 8.
Meanwhile, a noise attenuator 10 is disposed on an upper side of the cylinder 8 in order to attenuate noises generated from the cylinder 8.
The noise attenuator 10 is connected to a suction pipe 12 which is, in turn, connected to an accumulator (not shown).
The reciprocating compressor thus constructed, mainly being installed on a refrigerator, air conditioner or the like, sucks in refrigerant gas to compress the same for discharge thereafter, and when the rotor 2 is rotated by power supplied to the motor comprising the stator 2 and the rotor 3, the rotary shaft 6 is rotated in accordance with the rotation of the rotor 2.
As the rotary shaft 6 is rotated, so is the crank shaft 5 rotated, and when the crank shaft 5 is rotated, the connecting rod 9 begins a linear reciprocating motion.
When the connecting rod 9 starts the linear reciprocating motion, the piston 7 reciprocatively moves within the cylinder 8.
In other words, the piston performs an intake stroke for intaking the refrigerant gas into the cylinder 8 and a discharge stroke for compressing the refrigerant gas sucked into the cylinder 8 to thereafter discharge the same.
During the intake stroke, the refrigerant gas infused through the accumulator is sucked into the cylinder 8 through the intake pipe 12 and the noise attenuator 10.
The refrigerant gas sucked into the cylinder 8 is compressed by the piston 7 in high temperature and high pressure and is discharged outside of the cylinder 8 to thereby be supplied to a condenser (not shown).
In other words, the refrigerant gas is infused into the cylinder 8 through the head cover 4 disposed at one side of the cylinder 8 and through a suction valve (not shown) during the intake stroke, and the refrigerant gas, after being compressed in high temperature and high pressure, is discharged to the condenser (not shown) through a discharge valve (not shown) and the head cover 4 disposed at one side of the cylinder 8 during the discharge stroke.
As seen from the aforesaid, the noise generated by the closing and opening of the suction valve and the discharge valve during the intake and discharge strokes, and the noise is attenuated by the noise attenuator 10.
FIG. 2 is a sectional view for illustrating construction of a conventional noise attenuator 10.
According to FIG. 2, the conventional attenuator 10 comprises: an external case 11 having an inner space; a separation member 14 for partitioning the inner space into an upper chamber 13a and a lower chamber 13b; a suction hole or part 15 for interconnecting the suction pipe 12 (see FIG. 1) and the upper chamber 13a to thereby let the refrigerant gas to be infused into the upper chamber 13a from the suction pipe 12; a passage in the form of a connecting pipe 16 for piercing through the separation member 14 to thereby connect the upper chamber 13a and the lower chamber 13b; and passage in the form of infuse pipes 18a and 18b for supplying the refrigerant gas infused into the lower chamber 13b to the cylinder head 4 of a suction chamber 4a.
The reference numeral 4b designates a discharge chamber.
The noise attenuator 10 thus constructed is compelled to receives a noise generated by way of the closing and opening of the suction valve and the discharge valve disposed between the cylinder head 4 and the cylinder 8 (see FIG. 1), and the generated noise is attenuated in the course of passing through the infuse pipes 18a and 18b, lower chamber 13b, connecting pipe 106 and the upper chamber 13a which happens to have a cavity length of l.
At this time, the noise attenuator 10 has attenuated the noise as illustrated in solid lines in FIGS. 5 and 6.
According to each of FIGS. 5 and 6, the conventional noise attenuator 10 has shown a best noise transmission loss or reduction (the loss=inputted noise value-outputted noise value) at around 1,400 Hz.
Generally speaking, a higher transmission loss equates to a lower penetration efficiency of sound waves.
However, the noise generated by way of closing and opening of the suction valve and the discharge valve in the compressor is generally produced at around 500 Hz, which can hardly be attenuated by the noise attenuator 10 effectively.
In other words, as illustrated in FIGS. 5 and 6, the noise attenuator 10 has a transmission loss of less than 30 dB at around 500 Hz, and if it is assumed that the inputted noise value is 100 dB, the actual noise value transmitted to a user is a rather high noise of 70 dB.
As mentioned above, the conventional attenuator has a low transmission loss at around 500 Hz, so that the noise generated from the valves of the compressor is not only transmitted intact to the outside, but also the vibration resulting from the noise causes frequent inoperation, thereby causing degradation of the quality of the product.